The use of stuffer box crimpers to crimp synthetic fibers is generally known. Crimp is a waviness imparted to synthetic fibers during manufacture, and crimp level may be measured as crimps per unit of length, e.g. crimps per inch.
A conventional stuffer box crimper generally comprises a pair of cooperating cylindrical parallel nipping rollers forming a nip, a stuffer box, and a pair of cheek plates in contact with the lateral side surfaces of the nipping rollers to prevent the lateral egress of the fibers.
In general, synthetic fibers are pulled through a pair of nip rollers and forced into a stuffer box including, for example, a channel and a flapper at a distal end of the channel. The synthetic fibers are folded perpendicular to their direction of travel as they encounter the backpressure caused by the force stuffing the synthetic fibers against the flapper; thereby forming the crimped synthetic fibers.
A stuffer box may have a short life span due to the abrasive wear between the surface of the stuffer box and the synthetic fibers. The continuous requirement to replace the worn-out stuffer box is costly, and the friction and stick-slip behavior between the surface of the stuffer box and the synthetic fibers may also affect crimp uniformity.
Different techniques have been employed to achieve uniform crimped synthetic fibers to improve other characteristics thereof. For example, in filter tow production, uniform crimped tow may be employed to influence the openability of the tow, or the pressure drop or pressure drop (“PD”) variability of the filter rods made from such tow.
PD variability, a filter rod quality, refers to the PD uniformity of a large number of rods, and it is quantified by a Cv (coefficient of variation). Openability, a tow quality, refers to the ease of opening in the rodmaking equipment to completely deregister, or “bloom,” the tow. Openability is seldom quantified, but it is readily apparent.
Despite the efforts invested in developing stuffer box crimpers, there is a still a need for a cost effective stuffer box crimper with a longer wear-life, which facilitates the production of uniform crimped synthetic fibers. Furthermore, there is still a need for a cost effective method of crimping, which facilitates the production of uniform crimped synthetic fibers.